In some fuel cell based power generators, hydrogen is extracted from a fuel in the presence of water and then is introduced into a fuel cell to produce electricity. In such generators, hydrogen may leak to ambient even when power is not being drawn from the power generator. As hydrogen is lost, water migrates back to the fuel to replace the water consumed by the reaction that produced the hydrogen. If this process continues, energy may be slowly drained from a power generator, reducing the total energy available from the power generator for useful power generation.
Power generators based on hydrogen generators and proton exchange membrane (PEM) fuel cells may provide higher energy density than conventional power sources like batteries, but may have difficulty in quickly providing pulses of current. They may also be prone to high self discharge, low startup and sensitive to ambient humidity, making them impractical for some applications. Further, high cost of manufacture may have prevented wide commercialization.
Many electronic devices have intermittent and widely varying power requirements from essentially zero to quickly using short pulses of power as high as a few Watts. These power requirements make it difficult to design a commercially feasible fuel cell for a wide variety of applications. Such power sources should have a relatively long shelf life when not in use. It is desirable to increase the energy capacity of current power sources so as to decrease power supply replacement intervals and/or increase operating life, while also reducing the size and weight of the power source.